Question

Calculate the resistance of 100m long wire whose radius is 10mm specific resistivity of copper is 1.7×10 raise to power minus 8

Answer 1

R = ρL / A
= ρL / (π r²) ……[∵ cross section of wire is circular]
= 1.7 × 10⁻⁸ × 100 m / [π × (10 × 10⁻³ m)²]
= 0.0054 Ω

Resistance of wire is 0.0054 Ω